Silicon controlled rectifier

Abstract

A silicon controlled rectifier structure of polygonal layouts is provided. The polygonal first conductive type doped region is located in the middle of the polygonal second conductive type well. The first conductive type well shaped as a polygonal ring surrounds the second conductive type well and the second conductive type doped region is located within the first conductive type well and shaped as a polygonal ring concentric to the first conductive type well.